The present invention relates to a device for use with fraction collectors, and more specifically to a device for preventing spillage when switching from one collecting receptacle to the next.
Fraction collectors are widely used in many applications, such as in the field of liquid chromatography. A fraction collector is used for dispensing a flow of a liquid to a number of receptacles. The receptacles are typically constituted as test tubes mounted in a rack or as recesses formed in a plate. Two main working principles can be distinguished for fraction collectors: the rotatable collector wherein the receptacles are fed towards a dispensing means by a rotating movement, and the X-Y collector wherein the receptacles are fed towards a dispensing means by linear movements in one or two directions. Of course, these principles are the same as those for fraction collectors wherein the dispensing means is moving while the receptacles are at rest.
Regardless of the type of receptacle or fraction collector working principle, there is always a distance between each separate receptacle. Therefore, when switching from one receptacle to the next, a spillage of the dispensed liquid is likely to occur, especially in a case were the liquid flow is essentially continuous. There are numerous reasons for why such spillage is not desired: it could contain valuable substances, it could be a potential health hazard and the working area becomes messy.
Methods for avoiding the spillage are known. For example, in U.S. Pat. No. 4,077,444 to Gilson et al. there is described a valve and a valve operator that are used to discontinue a liquid flow through a dispensing tube in order to prevent spillage from the tube as it moves between positions. However, in certain applications, such as high precision liquid chromatography, interruption of the liquid flow during a hold time is a disadvantage. The performance of the liquid chromatography system is negatively affected due to the occurrence of diffusion of the components in the liquid volume held in the tubing near the dispensing means during the hold time.
It is also known to use a shunt valve to convey the liquid flow to waste during the receptacle change. This method has obviously the disadvantage that valuable substances may be present in the wasted flow, and consequently are lost.
Therefore, there is a need for a method and a device for preventing spillage when switching from one collecting receptacle to the next in a fraction collector.
In a first aspect, it is an object of the present invention to provide a method for preventing spillage when switching from one collecting receptacle to the next in a fraction collector.
This object is achieved with a method of the present invention.
According to the method of the invention, a liquid volume that should have been dispensed during a time interval necessary to switch receptacles is held in an expandable chamber. When the next receptacle is properly positioned to receive liquid, the liquid volume retained in the expandable chamber is added to the ongoing flow of liquid through the fraction collector to be dispensed into the receptacle.
In a second aspect of the present invention there is provided a device for preventing spillage when switching from one collecting receptacle to the next in a fraction collector.
In a third aspect of the present invention there is provided a fraction collector including a device for preventing spillage when switching from one collecting receptacle to the next.
In a fourth aspect of the present invention there is provided a liquid chromatography system including a device for preventing spillage when switching from one collecting receptacle to the next in a fraction collector.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples while indicating preferred embodiments of the invention are given by way of illustration only. Various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the detailed description below.
Specifically, it should be noted that the use of the method and device of the invention is illustrated within the field of liquid chromatography. However, it is just as useful within any other field of application wherein there is a desire to use a fraction collector without spillage when switching from one collecting receptacle to the next.